Human serum albumin (HSA) is the most abundant protein present in blood plasma, where its role is to contribute to the maintenance of osmotic pressure and to bind nutrients and metabolites, to thereby enable transport thereof. There is a large pharmaceutical and scientific interest in HSA, e.g. as a drug for treating hypoalbuminemia caused by a loss of albumin or a reduction in albumin synthesis, in hemorrhagic shock etc. In the earliest methods available, the HSA was purified from blood. However, such methods brought about problems, for example a sporadic supply of blood, economical disadvantages and contamination with undesirable substances such as hepatitis virus and not least AIDS virus. To avoid these problems, alternative methods based on recombinant DNA techniques have more recently been developed to produce recombinant HSA (rHSA). Even though a number of recombinant methods have been suggested, it has been shown that the purification of the rHSA from the fermentation broth is a crucial step and there is an ongoing need of improvements to this end.
EP 0 612 761 discloses a method of producing recombinant human serum albumin of high purity, which does not contain free non-antigenic contaminants. The method utilises hydrophobic interaction chromatography (HIC) under specified conditions combined with other steps such as ion exchange chromatography, treatment with boric acid or a salt thereof followed by ultrafiltration, and heat treatment. However, a series of that many steps will still be too complex and accordingly too expensive for satisfactory use in large-scale operation in industry.
EP 0 570 916 also discloses a process for producing recombinant human serum albumin by gene manipulation techniques, wherein purification is by a combination of steps in which a culture supernatant is subjected to ultrafiltration, heat treatment, acid treatment and another ultrafiltration, followed by subsequent treatments with a cation exchanger, a hydrophobic chromatography carrier and an anion exchanger and by salting out. However, similar to the above-mentioned patent, this purification scheme is too complex, time-consuming and accordingly too expensive to provide an efficient procedure for use in large-scale operation.
EP 0 699 687 discloses a method of purification of rHSA wherein culture medium is heat treated to inactivate proteases and then contacted with a fluidised bed of cation exchange particles. The eluent can subsequently be subject to ultrafiltration, HIC and anion exchange chromatography. However, use of a fluidised bed will require equipment different to the conventional packed bed chromatographic step. Accordingly, there is still a need of more efficient and economically attractive procedures for purification of rHSA from a culture broth.